The Family Medical Leave Act (FMLA) guarantees 12 weeks of unpaid leave every year to eligible employees who need it due to medical issues that they — or their family members — are suffering. That leave can be taken all at once or intermittently — which is something that many employers despise. Consequently, they may try to discourage it through either direct or indirect means whenever possible.

Intermittent leave is an absolute necessity for many people working in spite of their disabilities or chronic medical conditions. While it may inconvenience an employer if you have to take several days of the month off to go to chemotherapy treatments, see a bevy of specialists or because you suffer from intractable migraines, time taken under the FMLA cannot be legally held against you.

Nor can your employer legally make taking intermittent leave unduly burdensome — which employers sometimes try to do under the guise of ferreting out FMLA abuses. While your employer can require a note from your doctor verifying your need for leave, that rule isn’t without restrictions. For example, your employer isn’t entitled to specifics about your medical condition (unless you choose to disclose it). Also, once your need for intermittent leave is established, your employer can’t require a new doctor’s note every time you use it just to prove that you actually were out sick.

For example, imagine that your employer is concerned that you (or others) are abusing the FMLA in order to get a few “long weekends.” To that end, your employer wants a note from your doctor’s office if you happen to be sick or have an appointment on a Monday or a Friday. With intermittent leave, that’s unreasonable for your employer to demand. In fact, unless your circumstances have changed since you submitted your original certifying doctor’s letter or your employer has good cause to doubt the validity of your needs, an employer can only request a new doctor’s note every 30 days.

Disability discrimination at work comes in many different forms — including unreasonable demands for medical documentation when you need to use intermittent leave under the FMLA. If this happens to you, find out how you can hold your employer responsible.